Preparation method for 5-fluorin-2-hydroxyacetophenone

Abstract

The invention provides a preparation method for 5-fluorin-2-hydroxyacetophenone. The preparation method comprises the following steps of: performing double esterification on amino groups and phenolic hydroxy in one step by taking amino-phenol as a raw material; performing Fries rearrangement under the condition of aluminum chloride / sodium chloride; heating a hydrolyzate after performing fluorine diazotization to obtain finished 5-fluorin-2-hydroxyacetophenone. The preparation method has the advantages of low prices of raw materials, relatively mild reaction conditions, total yield of up to 54.5 percent and industrial production application value.

Description

technical field

[0001] The invention relates to the field of fluorine chemical industry, in particular to a synthesis method of 5-fluoro-2-hydroxyacetophenone. Background technique

[0002] 5-Fluoro-2-hydroxyacetophenone, also known as 2-acetyl-4-fluorophenol, is an important pharmaceutical intermediate, which can be used as a synthetic intermediate for various β receptor blockers, and has broad market prospects. The general preparation method reported so far is to use p-fluorophenol as a raw material, undergo acylation with hydroxyl groups, and then use Fries rearrangement to synthesize it. The synthesis of raw materials by this method is expensive, especially the fluorine atom on the aromatic ring is a strong electron-withdrawing group, which may have a great impact on the yield of acylation and rearrangement. Contents of the invention

[0003] The object of the present invention is to provide a method for the catalytic synthesis of 5-fluoro-2-hydroxyacetophenone starti...

Examples

Embodiment 1

[0016] Put 32.7g of p-aminophenol and 76.5g of acetic anhydride into 250mL of benzene, stir and heat, and react under reflux at 80°C for 3h. After the reaction was completed, the solvent was recovered by distillation under reduced pressure to dryness, cooled, and 300 L of water was added to precipitate a solid, which was filtered and dried to obtain 55.0 g of an off-white solid with a yield of 93.0%, m.p.151°C, and was directly used in the next reaction without purification.

Embodiment 2

[0018] The product prepared in Example 1 (38.6g, 0.2mol), anhydrous aluminum trichloride (80g, and sodium chloride (40g) were put into the reaction flask, stirred and heated to 120°C, and the reaction mixture was in the form of a thin paste. Accompanied by the release of a large amount of acid gas; keep the reaction for 3 hours, when no more gas is released, cool the reaction mixture to 60°C, slowly add 160mL of water to the mixture, vigorously stir, freeze, suction filter, and dry to light yellow Solid 36.3g, yield 94.0%, m.p.162°C.

Embodiment 3

[0020] Add (38.6 g, 0.2 mol) and hydrochloric acid (400 mL, 6 mol / L) obtained in the previous example into a 500 mL round-bottomed flask and keep under reflux for 6 h. After reflux, cool, adjust the pH value to 6-7, precipitate a solid, dry, and weigh to obtain 18.9 g of a solid with a yield of 75.6%, m.p.167°C.

technical field

[0001] The invention relates to the field of fluorine chemical industry, in particular to a synthesis method of 5-fluoro-2-hydroxyacetophenone. Background technique

[0002] 5-Fluoro-2-hydroxyacetophenone, also known as 2-acetyl-4-fluorophenol, is an important pharmaceutical intermediate, which can be used as a synthetic intermediate for various β receptor blockers, and has broad market prospects. The general preparation method reported so far is to use p-fluorophenol as a raw material, undergo acylation with hydroxyl groups, and then use Fries rearrangement to synthesize it. The synthesis of raw materials by this method is expensive, especially the fluorine atom on the aromatic ring is a strong electron-withdrawing group, which may have a great impact on the yield of acylation and rearrangement. Contents of the invention

[0003] The object of the present invention is to provide a method for the catalytic synthesis of 5-fluoro-2-hydroxyacetophenone starti...

Examples

Embodiment 1

[0016] Put 32.7g of p-aminophenol and 76.5g of acetic anhydride into 250mL of benzene, stir and heat, and react under reflux at 80°C for 3h. After the reaction was completed, the solvent was recovered by distillation under reduced pressure to dryness, cooled, and 300 L of water was added to precipitate a solid, which was filtered and dried to obtain 55.0 g of an off-white solid with a yield of 93.0%, m.p.151°C, and was directly used in the next reaction without purification.

Embodiment 2

[0018] The product prepared in Example 1 (38.6g, 0.2mol), anhydrous aluminum trichloride (80g, and sodium chloride (40g) were put into the reaction flask, stirred and heated to 120°C, and the reaction mixture was in the form of a thin paste. Accompanied by the release of a large amount of acid gas; keep the reaction for 3 hours, when no more gas is released, cool the reaction mixture to 60°C, slowly add 160mL of water to the mixture, vigorously stir, freeze, suction filter, and dry to light yellow Solid 36.3g, yield 94.0%, m.p.162°C.

Embodiment 3

[0020] Add (38.6 g, 0.2 mol) and hydrochloric acid (400 mL, 6 mol / L) obtained in the previous example into a 500 mL round-bottomed flask and keep under reflux for 6 h. After reflux, cool, adjust the pH value to 6-7, precipitate a solid, dry, and weigh to obtain 18.9 g of a solid with a yield of 75.6%, m.p.167°C.